General, Web category, VoiceOver Utility on Mac
Use the General pane of the Web category in VoiceOver Utility to specify what happens when a webpage opens.
To open VoiceOver Utility, press Command-F5 to turn VoiceOver on, then press VO-F8.
Note: VO represents the VoiceOver modifier. See Use the VoiceOver modifier.
When loading a new web page
Select what you want VoiceOver to do when you open a web page:
While a webpage loads
Choose what you want to hear while a web page is being displayed: Speak Progress, Play Tone, or Do Nothing.
By default, VoiceOver speaks the percentage of the webpage that is loaded.